The ISIS Mobile Wallet went live on Thursday, bringing NFC-powered shopping to consumers across the U.S. through a venture backed by three of the nation's top four carriers.

ISIS lets consumers make purchases at special point-of-sale terminals using a smartphone with Near Field Communication, a free enhanced SIM card and a free ISIS Android app. Developed by a joint venture of Verizon Wireless, AT&T and T-Mobile USA, and open to any mobile operator, the system lets customers use credit cards from any participating financial institution, activating multiple cards within the app and choosing the right one for each purchase.

The national rollout follows a pilot deployment in Salt Lake City and Austin, Texas, that began about a year ago. Contactless mobile payments have had a rocky road to mass use in the U.S., partly because the country's credit-card infrastructure is so well developed. ISIS is the carriers' entry into the emerging market against other systems, most prominently Google Wallet.

Backers of the technology say paying with a phone may be easier and more convenient for some consumers, but also opens the door to more personalized deals and shopping experiences as well as other financial transactions that can be made on the go. ISIS users can add coupons and loyalty cards to their wallets in the app, and some merchant partners are offering deals as part of the launch of the service. Encrypted payment credentials, a tamper-resistant SIM card and other features help to secure the process, and the ISIS Wallet can be suspended with one call, the venture said.

ISIS said there are more than 40 smartphones from the three participating carriers that are ready to set up with the service. Apple's iPhones, which don't have NFC chips, are conspicuously absent from the list. But ISIS said support is coming for iPhones and Microsoft Windows Phones. That support may come with a phone sleeve that incorporates an NFC chip.

The list of participating credit-card issuers is also short at the moment. Only Chase and American Express credit cards, plus the American Express Serve reloadable prepaid card, can be used with ISIS.

ISIS works at stores with contactless payment terminals, which are increasingly common, according to ISIS. The venture said 25 of the top 100 U.S. retailers have deployed such terminals or are rolling them out. Participants include Toys "R" Us, Jamba Juice and Coca-Cola, which has implemented contactless payments on vending machines.

To get started, users can get the enhanced SIM card from their carriers and download the app, which is available only from the Google Play store. Subscribers can go to the carrier's retail shop for hands-on assistance.